How to use SAPI4 in C#.net

Question

Hello,
 
I have a text-to-speech application and I want to be able to support SAPI version 4 as well as SAPI5.
 
I am using .NET 2.0 compatible, use COM interop (via the auto-generated SpeechLib.dll).
With this I am able to get only SAPI5 version voices, How to get SAPI4 version voices.
 
What would I need to use/do to make use of SAPI4 as well?
 
Thanks in advance for any help!